The importance of crank length to the cyclist.

[Martin318is]

Why would it matter? The argument is a theoretical one. Were Einstein's musing's about the behavior of light less important because he wasn't actually a light particle and able to travel at the speed of light?

Its a pretty valid question really - I mean previously you have shown that you are vague about what the main issues in criterium racing are and you seem to have trouble grasping the dynamics of bunch racing. (yes we know you have knowledge about pedalling but thats not the same thing)

It seems to me that as you get more theoretical in your comments you resolve all 'cycling' into time-trial style riding in an aerodynamic position. Whereas a lot of us reading this thread really don't care what works for a triathlete - many in fact don't consider a triathlete to be a cyclist (but thats another well known topic). Where you don't talk about a static riding position, you talk about solo long distance efforts, etc. Nothing much about events where reaction etc is important.

Regardless, I think you could have the discussion of what is the ideal crank length and cadence, etc for a TIMETRIALIST but that the answer to that question would through realistic necessity produce different numbers to those for a road racer and even quite possibly for a triathlete if you think about it.

 

[FrankDay]

Its a pretty valid question really - I mean previously you have shown that you are vague about what the main issues in criterium racing are and you seem to have trouble grasping the dynamics of bunch racing. (yes we know you have knowledge about pedalling but thats not the same thing)

What part of my original post was devoted to criterium (or BMX, or cyclocross) racing. It was clearly devoted to address time-trialing, which is not an insubstantial part of cycling and is the major part of triathlon (which if you haven't notices also includes cycling even though many of you here demean them because they don't have the same bike handling skills, probably because they don't need them)

It seems to me that as you get more theoretical in your comments you resolve all 'cycling' into time-trial style riding in an aerodynamic position. Whereas a lot of us reading this thread really don't care what works for a triathlete - many in fact don't consider a triathlete to be a cyclist (but thats another well known topic). Where you don't talk about a static riding position, you talk about solo long distance efforts, etc. Nothing much about events where reaction etc is important.

I think you were to do an actual literature search you would find that "reaction time" is also improved with shorter cranks. Your problem is you are arguing what you think should be the case for the areas you are interested in but don't have any real science to back up your bias. If any of you could actually point to some studies that show that power is improved for climbing with longer cranks or that reaction time for acceleration is improved with longer cranks then you could perhaps make an argument that under certain circumstances longer cranks would be better. It might very well be the case but why is my argument for the purpose of optimizing time-trialing be debased because you and other like to race criteriums.

Regardless, I think you could have the discussion of what is the ideal crank length and cadence, etc for a TIMETRIALIST but that the answer to that question would through realistic necessity produce different numbers to those for a road racer and even quite possibly for a triathlete if you think about it.

I have no problem with that, but I have seen no evidence that what is best for the time-trialist is not also best for everyone else. If you would like to make that argument then I am all ears.

 

[Martin318is]

I have no problem with that, but I have seen no evidence that what is best for the time-trialist is not also best for everyone else. If you would like to make that argument then I am all ears.

Just to illustrate what I am talking about - Would you agree? (roughly - dont bother attacking individual points in these groupings. The point I am making is the general case, not any one throwaway comment I have typed below)

1) that the goal for the timetrialist is to optimise crank length, cadence, aero position, training, breathing, etc, etc to get the best possible speed from point A to B in a solo event without blowing up (I am intentionally ignoring equations here because they just obfuscate the point). Where the end result of this would generally be that they have crossed the line and have nothing left to give.

2) that the goal of the triathlete is to do something very similar with just some of the differences being: They have already done a swim and have therefore partly fatigued muscles that are now used to support them in the TT, need to operate at a different % of their maximum in order to save energy for the run, need to protect certain muscles to use in the run, and have trained their leg muscles in a different way to a cyclist - thereby possibly causing a difference in the optimum firing pattern of those muscles.

3) that the goal of a road cyclist (and here I won't bother splitting into CT vs classic, etc due to longwindedness) is to conserve energy whereever possible and hide in the bunch as much as possible until it is time to either attack or sprint. And that when that attack or sprint happens it will occur at drastically different cadences and body positions as the preceeding 1-6 hours.

4) that the goal of a track cyclist is to maximise acceleration and speed through the application of power and torque and that the training required for a track sprint athlete is massively different to all other types I have listed.

Like I said, dont get stuck into the detail - just ask yourself whether there is general truth there. Certainly it could be said that what is best for one is not best for another, merely that what is good for one might be good for the other.

 

[Boeing]

Why would it matter? The argument is a theoretical one. Were Einstein's musing's about the behavior of light less important because he wasn't actually a light particle and able to travel at the speed of light?

choose your words wisely

"Theoretical":Concerned with or involving the theory of a subject or area of study rather than its practical application


unless you mean you are headed back to the drawing board.

 

[42x16ss]

I am sorry. Do you have any actual evidence that longer cranks are more powerful for an uphill time-trial? I know you think they are but do you have any supporting evidence for that contention.

Do you have any evidence that proves aerodynamics is more important than power when going uphill? I know you think it is but do you have any supporting evidence for that contention?

 

[Martin318is]

Do you have any evidence that proves aerodynamics is more important than power when going uphill? I know you think it is but do you have any supporting evidence for that contention?

besides, we all know that mass basically trumps the hell out of those two...

 

[FrankDay]

Just to illustrate what I am talking about - Would you agree? (roughly - dont bother attacking individual points in these groupings. The point I am making is the general case, not any one throwaway comment I have typed below)

1) that the goal for the timetrialist is to optimise crank length, cadence, aero position, training, breathing, etc, etc to get the best possible speed from point A to B in a solo event without blowing up (I am intentionally ignoring equations here because they just obfuscate the point). Where the end result of this would generally be that they have crossed the line and have nothing left to give.

That is reasonable description. The one caveate might be in a stage race where someone in GC contention might want to "save something" for the remaining stages.

2) that the goal of the triathlete is to do something very similar with just some of the differences being: They have already done a swim and have therefore partly fatigued muscles that are now used to support them in the TT, need to operate at a different % of their maximum in order to save energy for the run, need to protect certain muscles to use in the run, and have trained their leg muscles in a different way to a cyclist - thereby possibly causing a difference in the optimum firing pattern of those muscles.

I would disagree somewhat with this. While swimming certainly uses different muscles than cycling it is not clear to me that cycling is substantially different from running in how the muscles are used in firing pattern, cadence, or much else. My basis for saying this comes (and I hate to bring this up) from my PowerCranks experience. We have professional runners and University track squads using PowerCranks because the pattern so closely resembles what is required of the runner sans the impact. Triathletes, when they start using the cranks are generally seeing running improvement start in about 2 weeks, way before they see cycling improvement. Elite runners refer to optimum leg movement as "cycling" (do you want a link to a video?) Therefore, while many refer to triathletes holding back on the bike to "save themselves for the run" I simply see it as holding back on the bike because they have three more hours to race. I think they would hold back about the same if those three hours were, instead, added to the bike (180 miles instead of 180 km). What sets the Ironman triathlete apart from the time-trial cyclist, aside from the swimming, is that the typical time trial, instead of lasting one hour lasts 5 or so and then the racer still has a few more hours of racing to go before they can call it a day.

3) that the goal of a road cyclist (and here I won't bother splitting into CT vs classic, etc due to longwindedness) is to conserve energy whereever possible and hide in the bunch as much as possible until it is time to either attack or sprint. And that when that attack or sprint happens it will occur at drastically different cadences and body positions as the preceeding 1-6 hours.

Well, this all comes down to team tactics doesn't it. Isn't the goal of some of the riders to try to wear the other teams down or to gain an advantage in a break away. It seems to me your description of what a road cyclist tries to do only applies to those designated to win in a sprint but not to those who may have other team roles. And, when that sprint does occur I would say the the best sprinters also try to maximize aerodynamics. They aren't sprinting on the hoods but, rather, in the drops with their heads down. I would be surprised if Cavendish is the most powerful sprinter in the peloton. So, I see no great difference between what the sprinter is trying to do and what the time-trialist is trying to do other than the "warm-up" period before crunch time is quite different and the actual length of the "crunch time" is quite different.

4) that the goal of a track cyclist is to maximise acceleration and speed through the application of power and torque and that the training required for a track sprint athlete is massively different to all other types I have listed.

Are you saying a track sprinter doesn't care about aerodynamics? While the training might be completely different the goal is the same, to traverse the distance as fast as possible which requires the best combination of power and aerodynamics for the short time they are performing. I have stated before I think optimal crank length for sprinters is probably longer than for endurance athletes but why would one expect it to be longer than the 145 mm that Martin found to be most powerful in his "maximum power" study? Where is the advantage in using a crank length that presumably lowers power and probably makes aerodynamics worse just because the event only lasts 10 seconds?

Like I said, dont get stuck into the detail - just ask yourself whether there is general truth there. Certainly it could be said that what is best for one is not best for another, merely that what is good for one might be good for the other.

Haven't I emphasized that one can only know if what I propose offers a benefit to themselves if one experiments with the change? Most of those who have tried this experiment on themselves and posted their experience in this thread have seemingly been happy with what they have seen.

 

[oldborn]

I have a long time ago announced that where Frank Day and CoachFergie are concerned I am not acting in the capacity of Moderator and am instead just posting as a member. Any moderation actions will be performed by someone other than me.

And while we are throwing stuff like that around - your fake poor english is getting over the top. Particularly when a simple search shows posts where your english is very good. Dial it back a bit and you will have more impact. Just a friendly tip ;-)

I missed that Kafka Metamorphosis again.

Oh btw my English skills, you do not know that I have learned English watching porn movies and porn movies only for two weeks, and you must know that those actors does not talk too much (I mean it is not Laurence Olivier in some sorry *** tragedy).

Ok, there is some great Hungarian-German co-production lately with much more text, so I am on again.

 

[oldborn]

That is because you have such a long history of using whopping lies to sell your product that you have no credibility. Zero. Nada. Zilch. Your assertions are transparently fatuous. Your attacks on power meters are risible. Your attempt to portray yourself as open minded is a masquerade.



Dr. Venkman, you are a poor scientist. The plural of anecdote is not data. You don't have any data.

Your purpose here is the same as it is everywhere you spam: To bury questions about your bamboozle in a crap flood of posts where you feign objectivity while promoting ludicrous anecdotes and misconstruing studies, which are often poorly constructed.



The years and years of you of spamming forums, being told time and time again why your bogus claims are wrong, and rejecting every attempt by rational people to guide you to a path of sanity stands as unassailable proof that the above statement is a lie as big as the ones you use to support your products.



No. Your reason for starting these "discussions," if you can call them that, is to promote your snake oil products with a blizzard of anedotes, obfuscation of fact, and outright denial of the usefulness of any type of measurement or testing that will expose your fraud.



"It is difficult to get a man to understand something when his salary depends upon his not understanding it." -- Upton Beall Sinclair



In other words you track the number of thread views to see the result of your spamming.

Gro Deal, for you even Virgin Mary and Mother Teresa are Tea Party movement members, so your somehow brilliant insertion are relevant as Al Capone tax payer s guide book.

 

[Tapeworm]

...While swimming certainly uses different muscles than cycling it is not clear to me that cycling is substantially different from running in how the muscles are used in firing pattern, cadence, or much else...

Sports Physiology 101 fail.

Ok chaps, who wants to help Frank here?

 

[Martin318is]

Either way, it appears that you ignored my comment in bold and went ahead and discussed the components of the individual points and generaly glossed over the overall idea. So....

question: If as you believe, cycling and running use the same muscles the same way, then how do you reconcile the idea that your runners get improvements from cycling with powercranks rather than standard cranks? To me it appears blatantly obvious that this is evidence that the IS a difference between running and cycling with standard cranks.

However, who cares? I am a cyclist, not a runner, nor a triathlete. Improving performance in the run leg is meaningless to me

Also, you are mistaken, I did not focus on sprinters in my post. This points to the question of your experience with cycling. The term 'attack' refers to trying to break away - whether on flat, climb, descent, whatever - not sprinting. Also, cycling is a team sport at pro and semi-pro levels but most of us race as individuals. That means that if I want to soften the bunch, I need to do the work myself, etc.

Yes sprinters are on the drops and not the hoods (most of the time) - this is for leverage not aerodynamics. Ask any 5 road sprinters you like and they will say the same - and that includes Cav. Cav's success comes from including a low tuck forward over the bars on top of that.

Regarding track sprinters, you seem to assume that all they will do is wind up as fast as possible and then hold the speed to the line. What about slow speed handling such as track standing etc? Are you saying that a sub 140mm crank is more stable to balance on than a 165mm or larger? Leverage for accelerating from standstill?

The majority of your points treat the bicycle as though it is a static workplace where one may develope a position and maintain it for an entire event. This is not the case (and it is another thing that is event specific). Its also very clear that whilst you appear to understand triathletes, you have a lot of learning to do regarding other disciplines and you are not going to get that from research papers. Go to some mass start racers and pay attention to the pedalling demands and positioning of the riders.

 

[elapid]

I am just putting these published studies out there with no agenda. To make it very clear, I do not have qualifications in exercise physiology, biomechanics or engineering, and hence am not commenting on the methodology, validity or conclusions of these studies. I have no opinion on short cranks versus standard cranks, but I have highlighted some sections that I found interesting. These studies focus on power output, which will no doubt be a bone of contention for Frank, but also efficiency and fatigue at different crank lengths and earlier studies tried to tailor bike design, including crank length, to the size of the cyclist/ So, for what it is worth, below are the abstracts of published scientific studies on short cranks (some of them not so short) that I could find on a PubMed search:

STUDY 1

Med Sci Sports Exerc. 2011 Sep;43(9):1689-97.
Effect of crank length on joint-specific power during maximal cycling.

Barratt PR, Korff T, Elmer SJ, Martin JC.
Centre for Sports Medicine and Human Performance, Brunel University, Uxbridge, United Kingdom.

Abstract

Previous investigators have suggested that crank length has little effect on overall short-term maximal cycling power once the effects of pedal speed and pedaling rate are accounted for. Although overall maximal power may be unaffected by crank length, it is possible that similar overall power might be produced with different combinations of joint-specific powers. Knowing the effects of crank length on joint-specific power production during maximal cycling may have practical implications with respect to avoiding or delaying fatigue during high-intensity exercise.

PURPOSE:

The purpose of this study was to determine the effect of changes in crank length on joint-specific powers during short-term maximal cycling.

METHODS:

Fifteen trained cyclists performed maximal isokinetic cycling trials using crank lengths of 150, 165, 170, 175, and 190 mm. At each crank length, participants performed maximal trials at pedaling rates optimized for maximum power and at a constant pedaling rate of 120 rpm. Using pedal forces and limb kinematics, joint-specific powers were calculated via inverse dynamics and normalized to overall pedal power.

RESULTS:

ANOVAs revealed that crank length had no significant effect on relative joint-specific powers at the hip, knee, or ankle joints (P > 0.05) when pedaling rate was optimized. When pedaling rate was constant, crank length had a small but significant effect on hip and knee joint power (150 vs 190 mm only) (P < 0.05).

CONCLUSIONS:

These data demonstrate that crank length does not affect relative joint-specific power once the effects of pedaling rate and pedal speed are accounted for. Our results thereby substantiate previous findings that crank length per se is not an important determinant of maximum cycling power production.

STUDY 2

Fatigue during maximal sprint cycling: unique role of cumulative contraction cycles.

Tomas A, Ross EZ, Martin JC.
Department of Exercise and Sport Science, the University of Utah, Salt Lake City, UT 84112-0920, USA.

Abstract

Maximal cycling power has been reported to decrease more rapidly when performed with increased pedaling rates. Increasing pedaling rate imposes two constraints on the neuromuscular system: 1) decreased time for muscle excitation and relaxation and 2) increased muscle shortening velocity. Using two crank lengths allows the effects of time and shortening velocity to be evaluated separately.

PURPOSES:

We conducted this investigation to determine whether the time available for excitation and relaxation or the muscle shortening velocity was mainly responsible for the increased rate of fatigue previously observed with increased pedaling rates and to evaluate the influence of other possible fatiguing constraints.

METHODS:

Seven trained cyclists performed 30-s maximal isokinetic cycling trials using two crank lengths: 120 and 220 mm. Pedaling rate was optimized for maximum power for each crank length: 135 rpm for the 120-mm cranks (1.7 m x s(-1) pedal speed) and 109 rpm for the 220-mm cranks (2.5 m x s(-1) pedal speed). Power was recorded with an SRM power meter.

RESULTS:

Crank length did not affect peak power: 999 +/- 276 W for the 120-mm crank versus 1001 +/- 289 W for the 220-mm crank. Fatigue index was greater (58.6% +/- 3.7% vs 52.4% +/- 4.8%, P < 0.01), and total work was less (20.0 +/- 1.8 vs 21.4 +/- 2.0 kJ, P < 0.01) with the higher pedaling rate-shorter crank condition. Regression analyses indicated that the power for the two conditions was most highly related to cumulative work (r2 = 0.94) and to cumulative cycles (r2 = 0.99).

CONCLUSIONS:

These results support previous findings and confirm that pedaling rate, rather than pedal speed, was the main factor influencing fatigue. Our novel result was that power decreased by a similar increment with each crank revolution for the two conditions, indicating that each maximal muscular contraction induced a similar amount of fatigue.

STUDY 3

J Appl Physiol. 2002 Sep;93(3):823-8.
Determinants of metabolic cost during submaximal cycling.

McDaniel J, Durstine JL, Hand GA, Martin JC.
Department of Exercise Science, University of South Carolina, Columbia, South Carolina 29208, USA.

Abstract

The metabolic cost of producing submaximal cycling power has been reported to vary with pedaling rate. Pedaling rate, however, governs two physiological phenomena known to influence metabolic cost and efficiency: muscle shortening velocity and the frequency of muscle activation and relaxation. The purpose of this investigation was to determine the relative influence of those two phenomena on metabolic cost during submaximal cycling. Nine trained male cyclists performed submaximal cycling at power outputs intended to elicit 30, 60, and 90% of their individual lactate threshold at four pedaling rates (40, 60, 80, 100 rpm) with three different crank lengths (145, 170, and 195 mm). The combination of four pedaling rates and three crank lengths produced 12 pedal speeds ranging from 0.61 to 2.04 m/s. Metabolic cost was determined by indirect calorimetery, and power output and pedaling rate were recorded. A stepwise multiple linear regression procedure selected mechanical power output, pedal speed, and pedal speed squared as the main determinants of metabolic cost (R(2) = 0.99 +/- 0.01). Neither pedaling rate nor crank length significantly contributed to the regression model. The cost of unloaded cycling and delta efficiency were 150 metabolic watts and 24.7%, respectively, when data from all crank lengths and pedal speeds were included in a regression. Those values increased with increasing pedal speed and ranged from a low of 73 +/- 7 metabolic watts and 22.1 +/- 0.3% (145-mm cranks, 40 rpm) to a high of 297 +/- 23 metabolic watts and 26.6 +/- 0.7% (195-mm cranks, 100 rpm). These results suggest that mechanical power output and pedal speed, a marker for muscle shortening velocity, are the main determinants of metabolic cost during submaximal cycling, whereas pedaling rate (i.e., activation-relaxation rate) does not significantly contribute to metabolic cost.

STUDY 4

Eur J Appl Physiol. 2002 Jan;86(3):215-7.
Effects of crank length on maximal cycling power and optimal pedaling rate of boys aged 8-11 years.

Martin JC, Malina RM, Spirduso WW.
Department of Exercise and Sport Science, University of Utah, Salt Lake City 84112-0920, USA. Jim.Martin@health.utah.edu

Abstract

It is generally reported that cycle crank length affects maximal cycling power of adults and that optimal crank length is related to leg length. This suggests that the use of standard length cycle cranks may provide nonoptimal test conditions for children. The purpose of this study was to determine the effects of cycle-crank length on maximal cycling power and optimal pedaling rate of 17 boys aged 8-11 years. The boys performed maximal cycle ergometry with standard (170 mm) cycle cranks and with a crank length that was 20% of estimated leg length (LL20). Power produced when using the 170 mm cranks [mean (SEM)] [364 (18) W] did not differ from that produced with the LL20 cranks [366 (19)]. Optimal pedaling rate was significantly greater for the LL20 cranks [129 (4) rpm] than for the 170 mm cranks [114 (4) rpm]. These data suggest that standard 170 mm cranks do not compromise maximal power measurements in boys aged 8-11 years so that the test apparatus does not bias physiological or developmental inferences made from tests of maximal cycling power.

 

[elapid]

STUDY 5

Eur J Appl Physiol. 2001 May;84(5):413-8.
Determinants of maximal cycling power: crank length, pedaling rate and pedal speed.

Martin JC, Spirduso WW.
University of Utah, Department of Exercise and Sport Science, 250S. 1850E. Rm. 200, Salt Lake City, UT.

Abstract

The purpose of this investigation was to determine the effects of cycle crank length on maximum cycling power, optimal pedaling rate, and optimal pedal speed, and to determine the optimal crank length to leg length ratio for maximal power production. Trained cyclists (n = 16) performed maximal inertial load cycle ergometry using crank lengths of 120, 145, 170, 195, and 220 mm. Maximum power ranged from a low of 1149 (20) W for the 220-mm cranks to a high of 1194 (21) W for the 145-mm cranks. Power produced with the 145- and 170-mm cranks was significantly (P < 0.05) greater than that produced with the 120- and 220-mm cranks. The optimal pedaling rate decreased significantly with increasing crank length, from 136 rpm for the 120-mm cranks to 110 rpm for the 220-mm cranks. Conversely, optimal pedal speed increased significantly with increasing crank length, from 1.71 m/s for the 120-mm cranks to 2.53 m/s for the 220-mm cranks. The crank length to leg length and crank length to tibia length ratios accounted for 20.5% and 21.1% of the variability in maximum power, respectively. The optimal crank length was 20% of leg length or 41% of tibia length. These data suggest that pedal speed (which constrains muscle shortening velocity) and pedaling rate (which affects muscle excitation state) exert distinct effects that influence muscular power during cycling. Even though maximum cycling power was significantly affected by crank length, use of the standard 170-mm length cranks should not substantially compromise maximum power in most adults.

STUDY 6

J Biomech. 2000 Aug;33(8):969-74.
A governing relationship for repetitive muscular contraction.

Martin JC, Brown NA, Anderson FC, Spirduso WW.
Department of Exercise Science, School of Public Health, The University of South Carolina, Columbia 29208, USA.

Abstract

During repetitive contractions, muscular work has been shown to exhibit complex relationships with muscle strain length, cycle frequency, and muscle shortening velocity. Those complex relationships make it difficult to predict muscular performance for any specific set of movement parameters. We hypothesized that the relationship of impulse with cyclic velocity (the product of shortening velocity and cycle frequency) would be independent of strain length and that impulse-cyclic velocity relationships for maximal cycling would be similar to those of in situ muscle performing repetitive contraction. Impulse and power were measured during maximal cycle ergometry with five cycle-crank lengths (120-220mm). Kinematic data were recorded to determine the relationship of pedal speed with joint angular velocity. Previously reported in situ data for rat plantaris were used to calculate values for impulse and cyclic velocity. Kinematic data indicated that pedal speed was highly correlated with joint angular velocity at the hip, knee, and ankle and was, therefore, considered a valid indicator of muscle shortening velocity. Cycling impulse-cyclic velocity relationships for each crank length were closely approximated by a rectangular hyperbola. Data for all crank lengths were also closely approximated by a single hyperbola, however, impulse produced on the 120mm cranks differed significantly from that on all other cranks. In situ impulse-cyclic velocity relationships exhibited similar characteristics to those of cycling. The convergence of the impulse-cyclic velocity relationships from most crank and strain lengths suggests that impulse-cyclic velocity represents a governing relationship for repetitive muscular contraction and thus a single equation can predict muscle performance for a wide range of functional activities. The similarity of characteristics exhibited by cycling and in situ muscle suggests that cycling can serve as a window though which to observe basic muscle function and that investigators can examine similar questions with in vivo and in situ models.

STUDY 7

Eur J Appl Physiol. 2010 Jan;108(1):177-82. Epub 2009 Sep 22.
Influence of crank length on cycle ergometry performance of well-trained female cross-country mountain bike athletes.

Macdermid PW, Edwards AM.
Universal College of Learning, Palmerston North, New Zealand. p.macdermid@ucol.ac.nz

Abstract

The aim of this study was to determine the differential effects of three commonly used crank lengths (170, 172.5 and 175 mm) on performance measures relevant to female cross-country mountain bike athletes (n = 7) of similar stature. All trials were performed in a single blind and balanced order with a 5- to 7-day period between trials. Both saddle height and fore-aft position to pedal axle distance at a crank angle of 90 degrees was controlled across all trials. The laboratory tests comprised a supra-maximal (peak power-cadence); an isokinetic (50 rpm) test; and a maximal test of aerobic capacity. The time to reach supra-maximal peak power was significantly (P < 0.05) shorter in the 170 mm (2.57 +/- 0.79 s) condition compared to 175 mm (3.29 +/- 0.76 s). This effect represented a mean performance advantage of 27.8% for 170 mm compared to 175 mm. There was no further inter-condition differences between performance outcome measurements derived for the isokinetic (50 rpm) maximum power output, isokinetic (50 rpm) mean power output or indices of endurance performance. The decreased time to peak power with the greater rate of power development in the 170 mm condition suggests a race advantage may be achieved using a shorter crank length than commonly observed. Additionally, there was no impediment to either power output produced at low cadences or indices of endurance performance using the shorter crank length and the advantage of being able to respond quickly to a change in terrain could be of strategic importance to elite athletes.

STUDY 8

Exp Brain Res. 2003 Oct;152(3):393-403. Epub 2003 Aug 1.
Neuromuscular and biomechanical coupling in human cycling: adaptations to changes in crank length.

Mileva K, Turner D.
Sport and Exercise Science Research Centre, Faculty of Engineering Science and Technology, South Bank University, 103 Borough Road, London, SE1 0AA, UK.

Abstract

This study exploited the alterations in pedal speed and joints kinematics elicited by changing crank length (CL) to test how altered task mechanics during cycling will modulate the muscle activation characteristics in human rectus femoris (RF), biceps femoris long head (BF), soleus (SOL) and tibialis anterior (TA). Kinetic (torque), kinematic (joint angle) and muscle activity (EMG) data were recorded simultaneously from both legs of 10 healthy adults (aged 20-38 years) during steady-state cycling at ~60 rpm and 90-100 W with three symmetrical CLs (155 mm, 175 mm and 195 mm). The CL elongation (DeltaCL) resulted in similar increases in the knee joint angles and angular velocities during extension and flexion, whilst the ankle joint kinematics was significantly influenced only during extension. DeltaCL resulted in significantly reduced amplitude and prolonged duration of BF EMG, increased mean SOL and TA EMG amplitudes, and shortened SOL activity time. RF activation parameters and TA activity duration were not significantly affected by DeltaCL. Thus total SOL and RF EMG activities were similar with different CLs, presumably enabling steady power output during extension. Higher pedal speeds demand an increased total TA EMG activity and decreased total BF activity to propel the leg through flexion into extension with a greater degree of control over joint stability. We concluded that the proprioceptive information about the changes in the cycling kinematics is used by central neural structures to adapt the activation parameters of the individual muscles to the kinetic demands of the ongoing movement, depending on their biomechanical function.

 

[elapid]

STUDY 9

J Sports Sci. 2000 Mar;18(3):153-61.
The effect of pedal crank arm length on joint angle and power production in upright cycle ergometry.

Too D, Landwer GE.
Department of Physical Education and Sport, State University of New York at Brockport, 14420-2989, USA.

Abstract

The aim of this study was to determine the effect of five pedal crank arm lengths (110, 145, 180, 230 and 265 mm) on hip, knee and ankle angles and on the peak, mean and minimum power production of 11 males (26.6+/-3.8 years, 179+/-8 cm, 79.6+/-9.5 kg) during upright cycle ergometry. Computerized 30 s Wingate power tests were performed on a free weight Monark cycle ergometer against a resistance of 8.5% body weight. Joint angles were determined, with an Ariel Performance Analysis System, from videotape recorded at 100 Hz. Repeated-measures analysis of variance and contrast comparisons revealed that, with increasing crank arm lengths, there was a significant decrement in the minimum hip and knee angles, a significant increment in the ranges of motion of the joints, and a parabolic curve to describe power production. The largest peak and mean powers occurred with a crank arm length of 180 mm. We conclude that 35 mm changes in pedal crank arm length significantly alter both hip and knee joint angles and thus affect cycling performance.

STUDY 10

J Sports Sci. 1996 Apr;14(2):139-57.
Maximal muscle power output in cycling: a modelling approach.

Yoshihuku Y, Herzog W.
Department of Natural Sciences, College of Engineering, Chubu University, Aichi, Japan.

Abstract

This study sought to find the optimal design parameters for a bicycle-rider system (crank length, pelvic inclination, seat height and rate of crank rotation) that maximise the power output from muscles of the human lower limb during cycling. The human lower limb was modelled as a planar system of five rigid bodies connected by four frictionless pin joints and driven by seven functional muscle groups. The muscles were assumed to behave according to an adapted form of Hill's (1938) equation, incorporating the muscle force-length relation. The force-length relation and the values of length that served as input into the relations of the various muscles were defined in the following two ways: (1) the force-length relation was parabolic, based on the experiment of Woittiez et al. (1984), and the length was defined as the whole muscle length; and (2) the force-length relation was expressed as a combination of lines, based on the cross-bridge theory, and the length was defined as muscle fibre length. In the second definition, the joint configurations at which four of the seven muscle groups reached optimal length (i.e. the length at which the muscle can exert maximal isometric force) were further given in two ways. The first way was consistent with a previous study from this laboratory (Yoshihuku and Herzog, 1990); the second way relied on unpublished experimental data. The dependence of the average power on the design parameters and definitions of the force-length relation and muscle length was examined. Maximal average power for one full crank rotation with a crank length of 0.17 m was found to be about 1300 W for definition 1 and 1000 W for definition 2. The average power was more sensitive to changes in design parameters in definition 2 than definition 1. The optimal rate of crank rotation with a crank length of 0.17 m was 18.4 rad s-1 (176 rev min-1) for definition 1 (this value is different from the result of the previous study due to revisions in input for two muscle groups), and 15.2 rad s-1 (145 rev min-1) and 14.6 rad s-1 (139 rev min-1) for definition 2.

STUDY 11

J Biomech. 1989;22(11-12):1151-61.
Multivariable optimization of cycling biomechanics.

Gonzalez H, Hull ML.
Department of Mechanical Engineering, University of California, Davis 95616.

Abstract

Relying on a biomechanical model of the lower limb which treats the leg-bicycle system as a five-bar linkage constrained to plane motion, a cost function derived from the joint moments developed during cycling is computed. At constant average power of 200 W, the effect of five variables on the cost function is studied. The five variables are pedalling rate, crank arm length, seat tube angle, seat height, and longitudinal foot position on the pedal. A sensitivity analysis of each of the five variables shows that pedalling rate is the most sensitive, followed by the crank arm length, seat tube angle, seat height, and longitudinal foot position on the pedal (the least sensitive). Based on Powell's method, a multivariable optimization search is made for the combination of variable values which minimize the cost function. For a rider of average anthropometry (height 1.78 m, weight 72.5 kg), a pedalling rate of 115 rev min-1, crank arm length of 0.140 m, seat tube angle of 76 degrees, seat height plus crank arm length equal to 97% of trochanteric leg length, and longitudinal foot position on the pedal equal to 54% of foot length correspond to the cost function global minimum. The effect of anthropometric parameter variations is also examined and these variations influence the results significantly. The optimal crank arm length, seat height, and longitudinal foot position on the pedal increase as the size of rider increases whereas the optimal cadence and seat tube angle decrease as the rider's size increases. The dependence of optimization results on anthropometric parameters emphasizes the importance of tailoring bicycle equipment to the anthropometry of the individual.

STUDY 12

J Biomech. 1988;21(10):839-49.
Bivariate optimization of pedalling rate and crank arm length in cycling.

Hull ML, Gonzalez H.
Department of Mechanical Engineering, University of California, Davis 95616.

Abstract

The contribution of this paper is a bivariate optimization of cycling performance. Relying on a biomechanical model of the lower limb, a cost function derived from the joint moments developed during cycling is computed. At constant average power, both pedalling rate (i.e. rpm) and crank arm length are systematically varied to explore the relation between these variables and the cost function. A crank arm length of 170 mm and pedalling rate of 100 rpm correspond closely to the cost function minimum. In cycling situations where the rpm deviates from 100 rpm, however, crank arms of length other than 170 mm yield minimum cost function values. In addition, the sensitivity of optimization results to both increased power and anthropometric parameter variations is examined. At increased power, the cost function minimum is more strongly related to the pedalling rate, with higher pedalling rates corresponding to the minimum. Anthropometric parameter variations influence the results significantly. In general it is found that the cost function minimum for tall people occurs at longer crank arm lengths and lower pedalling rates than the length and rate for short people.

 

[FrankDay]

Either way, it appears that you ignored my comment in bold and went ahead and discussed the components of the individual points and generaly glossed over the overall idea. So....

I did not ignore your comments in bold. I commented on those points I thought needed to be commented on to further the discussion.
[/QUOTE]

question: If as you believe, cycling and running use the same muscles the same way, then how do you reconcile the idea that your runners get improvements from cycling with powercranks rather than standard cranks? To me it appears blatantly obvious that this is evidence that the IS a difference between running and cycling with standard cranks. [/QUOTE]Why are PowerCranks more effective at helping runners than standard cranks? That is easy. Using PowerCranks is closer to running that standard cranks (at least how most people use standard cranks) because of what the PC's force the rider to do, unweight and lift the foot on the backstroke, something runners also must do (and the better runners generally lift it higher). PC's also allow the runner to train these unweighting muscles at running cadences and for running durations, be that 10 seconds or 10 hours. There are other similarities also but I think this is the major one.

However, who cares? I am a cyclist, not a runner, nor a triathlete. Improving performance in the run leg is meaningless to me

Apparently you haven't considered that being "more like a runner" (as described above) might also help your cycling. Have you ever wondered why runners generally have higher VO2 max than cyclists? Could it be runners use more muscles than cyclists? Could cyclists better train and use any of those muscles in their cycling?

Also, you are mistaken, I did not focus on sprinters in my post. This points to the question of your experience with cycling. The term 'attack' refers to trying to break away - whether on flat, climb, descent, whatever - not sprinting. Also, cycling is a team sport at pro and semi-pro levels but most of us race as individuals. That means that if I want to soften the bunch, I need to do the work myself, etc.

Whatever. If you think aerodynamics are not important for a rider on a break or trying to bridge a gap then so be it. I just happen to think that the only time it is not important in cycling is when one is in the bunch. That really helps the weak rider trying to not get dropped but it doesn't help many to win.

Yes sprinters are on the drops and not the hoods (most of the time) - this is for leverage not aerodynamics. Ask any 5 road sprinters you like and they will say the same - and that includes Cav. Cav's success comes from including a low tuck forward over the bars on top of that.

While they may not think this is for aerodynamics, it helps their aerodynamics. Cav probably has the best aerodynamics of the bunch both because of his position when he sprints and his size. He certainly is not the most powerful, again because of his size. He seems to do pretty well.

Regarding track sprinters, you seem to assume that all they will do is wind up as fast as possible and then hold the speed to the line. What about slow speed handling such as track standing etc? Are you saying that a sub 140mm crank is more stable to balance on than a 165mm or larger? Leverage for accelerating from standstill?

Well, I don't know if it is more stable for balancing but I can state with certainty it has nothing to do with leverage or acceleration because that has more to do with the total leverage between the pedal and the ground. This is also affected by gearing so someone on shorter cranks will need smaller gears if they want equivalent acceleration. Of course, this will mean lower top speed won't it. My goodness, isn't it strange that cycling is all about trade off's. If a rider has poor acceleration but good top end speed perhaps they might want to use different tactics. Isn't the idea to race to your strengths and your opponents weaknesses, if you can?

The majority of your points treat the bicycle as though it is a static workplace where one may develope a position and maintain it for an entire event. This is not the case (and it is another thing that is event specific). Its also very clear that whilst you appear to understand triathletes, you have a lot of learning to do regarding other disciplines and you are not going to get that from research papers. Go to some mass start racers and pay attention to the pedalling demands and positioning of the riders.

If you say so. I personally see you (and others) as seeing the bicycle as this thing that was optimized years ago to which the cyclist must adapt. While I am trying to look at what can be done to the bicycle, within the rules, to optimize the cyclist. Either way, what does your point have to do with the point I am trying to make with this thread?

 

[FrankDay]

STUDY 9

J Sports Sci. 2000 Mar;18(3):153-61.
The effect of pedal crank arm length on joint angle and power production in upright cycle ergometry.

Too D, Landwer GE.
Department of Physical Education and Sport, State University of New York at Brockport, 14420-2989, USA.

Abstract

The aim of this study was to determine the effect of five pedal crank arm lengths (110, 145, 180, 230 and 265 mm) on hip, knee and ankle angles and on the peak, mean and minimum power production of 11 males (26.6+/-3.8 years, 179+/-8 cm, 79.6+/-9.5 kg) during upright cycle ergometry. … The largest peak and mean powers occurred with a crank arm length of 180 mm. We conclude that 35 mm changes in pedal crank arm length significantly alter both hip and knee joint angles and thus affect cycling performance.

upright cycling. What happens when the rider repeats this test in an aerodynamic position? What happens when asked to go longer than 30 seconds?

STUDY 10

J Sports Sci. 1996 Apr;14(2):139-57.
Maximal muscle power output in cycling: a modelling approach.

Yoshihuku Y, Herzog W.
Department of Natural Sciences, College of Engineering, Chubu University, Aichi, Japan.

Abstract

This study sought to find the optimal design parameters for a bicycle-rider system (crank length, pelvic inclination, seat height and rate of crank rotation) that maximise the power output from muscles of the human lower limb during cycling. T … The dependence of the average power on the design parameters and definitions of the force-length relation and muscle length was examined. Maximal average power for one full crank rotation with a crank length of 0.17 m was found to be about 1300 W for definition 1 and 1000 W for definition 2. The average power was more sensitive to changes in design parameters in definition 2 than definition 1. The optimal rate of crank rotation with a crank length of 0.17 m was 18.4 rad s-1 (176 rev min-1) for definition 1 (this value is different from the result of the previous study due to revisions in input for two muscle groups), and 15.2 rad s-1 (145 rev min-1) and 14.6 rad s-1 (139 rev min-1) for definition 2.

cool. Now their problem is to show that their model (be it definition1 or 2) predicts the real world. Until a model has been shown to be valid it seems a bit premature to use it to make a point don't you think?

STUDY 11

J Biomech. 1989;22(11-12):1151-61.
Multivariable optimization of cycling biomechanics.

Gonzalez H, Hull ML.
Department of Mechanical Engineering, University of California, Davis 95616.

Abstract

Relying on a biomechanical model of the lower limb which treats the leg-bicycle system as a five-bar linkage constrained to plane motion, a cost function derived from the joint moments developed during cycling is computed. A … For a rider of average anthropometry (height 1.78 m, weight 72.5 kg), a pedalling rate of 115 rev min-1, crank arm length of 0.140 m, seat tube angle of 76 degrees, seat height plus crank arm length equal to 97% of trochanteric leg length, and longitudinal foot position on the pedal equal to 54% of foot length correspond to the cost function global minimum. The effect of anthropometric parameter variations is also examined and these variations influence the results significantly. The optimal crank arm length, seat height, and longitudinal foot position on the pedal increase as the size of rider increases whereas the optimal cadence and seat tube angle decrease as the rider's size increases. The dependence of optimization results on anthropometric parameters emphasizes the importance of tailoring bicycle equipment to the anthropometry of the individual.

Wow, Average rider using a pedal rate of 115 rpm and crank length of 140 mm? And they find that optimum crank length increases with rider height. Wonder if their model will hold up in the real world?

STUDY 12

J Biomech. 1988;21(10):839-49.
Bivariate optimization of pedalling rate and crank arm length in cycling.

Hull ML, Gonzalez H.
Department of Mechanical Engineering, University of California, Davis 95616.

Abstract

The contribution of this paper is a bivariate optimization of cycling performance. Relying on a biomechanical model of the lower limb, a cost function derived from the joint moments developed during cycling is computed. … A crank arm length of 170 mm and pedalling rate of 100 rpm correspond closely to the cost function minimum. In cycling situations where the rpm deviates from 100 rpm, however, crank arms of length other than 170 mm yield minimum cost function values. In addition, the sensitivity of optimization results to both increased power and anthropometric parameter variations is examined. At increased power, the cost function minimum is more strongly related to the pedalling rate, with higher pedalling rates corresponding to the minimum. Anthropometric parameter variations influence the results significantly. In general it is found that the cost function minimum for tall people occurs at longer crank arm lengths and lower pedalling rates than the length and rate for short people.

Another model waiting to see if it predicts the real world. Until then, as I stated before, until a model has been shown to be valid it seems a bit premature to use it to make a point, don't you think?

 

[Boeing]

Frank;

I don't discount your theory because there is simply no convincing evidence to support or reject it yet my friend. Meaning your presentation and logic is flawed. That is the point many of us are trying to convey to you. give me something to chew on

How can you proceed to pick apart a study with documented results based on a sample survey which supports both the pros and cons of it's assertions when in fact you do nothing of the sort in your own arguments? It's like coachfargo saying his students go faster because they are his students

elapid thanks for that study. nice post

I am still chewing on this one

These results support previous findings and confirm that pedaling rate, rather than pedal speed, was the main factor influencing fatigue. Our novel result was that power decreased by a similar increment with each crank revolution for the two conditions, indicating that each maximal muscular contraction induced a similar amount of fatigue.

Can we talk about this a little because it seems to support longer cranks right? am I reading this correctly? Study 2 btw

 

[Boeing]

upright cycling. What happens when the rider repeats this test in an aerodynamic position? What happens when asked to go longer than 30 seconds?

cool. Now their problem is to show that their model (be it definition1 or 2) predicts the real world. Until a model has been shown to be valid it seems a bit premature to use it to make a point don't you think?

Wow, Average rider using a pedal rate of 115 rpm and crank length of 140 mm? And they find that optimum crank length increases with rider height. Wonder if their model will hold up in the real world?
Another model waiting to see if it predicts the real world. Until then, as I stated before, until a model has been shown to be valid it seems a bit premature to use it to make a point, don't you think?

premature is presenting theory with no documented study in a sample study to confirm of disprove ones claims Frank simple logic. The study posted does just that if you agree with findings or not. you have done nothing to discredit it

 

[FrankDay]

STUDY 5

Eur J Appl Physiol. 2001 May;84(5):413-8.
Determinants of maximal cycling power: crank length, pedaling rate and pedal speed.

Martin JC, Spirduso WW.
University of Utah, Department of Exercise and Sport Science, 250S. 1850E. Rm. 200, Salt Lake City, UT.

Abstract

The purpose of this investigation was to determine the effects of cycle crank length on maximum cycling power, optimal pedaling rate, and optimal pedal speed, and to determine the optimal crank length to leg length ratio for maximal power production. Trained cyclists (n = 16) performed maximal inertial load cycle ergometry using crank lengths of 120, 145, 170, 195, and 220 mm. Maximum power ranged from a low of 1149 (20) W for the 220-mm cranks to a high of 1194 (21) W for the 145-mm cranks. Power produced with the 145- and 170-mm cranks was significantly (P < 0.05) greater than that produced with the 120- and 220-mm cranks. The optimal pedaling rate decreased significantly with increasing crank length, from 136 rpm for the 120-mm cranks to 110 rpm for the 220-mm cranks. …. Even though maximum cycling power was significantly affected by crank length, use of the standard 170-mm length cranks should not substantially compromise maximum power in most adults.

Max power occurred at 145 mm. Yet he concludes that the the decrease in power is "not substantial" "for most riders" as if he doesn't care if riders optimize power or not.

STUDY 6

J Biomech. 2000 Aug;33(8):969-74.
A governing relationship for repetitive muscular contraction.

Martin JC, Brown NA, Anderson FC, Spirduso WW.
Department of Exercise Science, School of Public Health, The University of South Carolina, Columbia 29208, USA.

Abstract

During repetitive contractions, muscular work has been shown to exhibit complex relationships with muscle strain length, cycle frequency, and muscle shortening velocity. Those complex relationships make it difficult to predict muscular performance for any specific set of movement parameters. We hypothesized that the relationship of impulse with cyclic velocity (the product of shortening velocity and cycle frequency) would be independent of strain length and that impulse-cyclic velocity relationships for maximal cycling would be similar to those of in situ muscle performing repetitive contraction. … , impulse produced on the 120mm cranks differed significantly from that on all other cranks. In situ impulse-cyclic velocity relationships exhibited similar characteristics to those of cycling. The convergence of the impulse-cyclic velocity relationships from most crank and strain lengths suggests that impulse-cyclic velocity represents a governing relationship for repetitive muscular contraction and thus a single equation can predict muscle performance for a wide range of functional activities. The similarity of characteristics exhibited by cycling and in situ muscle suggests that cycling can serve as a window though which to observe basic muscle function and that investigators can examine similar questions with in vivo and in situ models.

Your point here? 120 mm cranks were significantly different. Different how? What was the riding position of the participants?

STUDY 7

Eur J Appl Physiol. 2010 Jan;108(1):177-82. Epub 2009 Sep 22.
Influence of crank length on cycle ergometry performance of well-trained female cross-country mountain bike athletes.

Macdermid PW, Edwards AM.
Universal College of Learning, Palmerston North, New Zealand. p.macdermid@ucol.ac.nz

Abstract

The aim of this study was to determine the differential effects of three commonly used crank lengths (170, 172.5 and 175 mm) on performance measures relevant to female cross-country mountain bike athletes (n = 7) of similar stature .… The time to reach supra-maximal peak power was significantly (P < 0.05) shorter in the 170 mm (2.57 +/- 0.79 s) condition compared to 175 mm (3.29 +/- 0.76 s). This effect represented a mean performance advantage of 27.8% for 170 mm compared to 175 mm. … The decreased time to peak power with the greater rate of power development in the 170 mm condition suggests a race advantage may be achieved using a shorter crank length than commonly observed. Additionally, there was no impediment to either power output produced at low cadences or indices of endurance performance using the shorter crank length and the advantage of being able to respond quickly to a change in terrain could be of strategic importance to elite athletes.

Hmmm. A "reaction" advantage to shorter cranks. One might reasonably ask the question as to whether this advantage continues with even shorter cranks. The range was too small to be able to discern whether there might be a power advantage.

STUDY 8

Exp Brain Res. 2003 Oct;152(3):393-403. Epub 2003 Aug 1.
Neuromuscular and biomechanical coupling in human cycling: adaptations to changes in crank length.

Mileva K, Turner D.
Sport and Exercise Science Research Centre, Faculty of Engineering Science and Technology, South Bank University, 103 Borough Road, London, SE1 0AA, UK.

Abstract

This study exploited the alterations in pedal speed and joints kinematics elicited by changing crank length (CL) to test how altered task mechanics during cycling will modulate the muscle activation characteristics in human rectus femoris (RF), biceps femoris long head (BF), soleus (SOL) and tibialis anterior (TA). Kinetic (torque), kinematic (joint angle) and muscle activity (EMG) data were recorded simultaneously from both legs of 10 healthy adults (aged 20-38 years) during steady-state cycling at ~60 rpm and 90-100 W with three symmetrical CLs (155 mm, 175 mm and 195 mm). The CL elongation (DeltaCL) resulted in similar increases in the knee joint angles and angular velocities during extension and flexion, whilst the ankle joint kinematics was significantly influenced only during extension. DeltaCL resulted in significantly reduced amplitude and prolonged duration of BF EMG, increased mean SOL and TA EMG amplitudes, and shortened SOL activity time. RF activation parameters and TA activity duration were not significantly affected by DeltaCL. Thus total SOL and RF EMG activities were similar with different CLs, presumably enabling steady power output during extension. Higher pedal speeds demand an increased total TA EMG activity and decreased total BF activity to propel the leg through flexion into extension with a greater degree of control over joint stability. We concluded that the proprioceptive information about the changes in the cycling kinematics is used by central neural structures to adapt the activation parameters of the individual muscles to the kinetic demands of the ongoing movement, depending on their biomechanical function.

Not sure what this paper has to do with this argument.

 

[FrankDay]

I am just putting these published studies out there with no agenda. To make it very clear, I do not have qualifications in exercise physiology, biomechanics or engineering, and hence am not commenting on the methodology, validity or conclusions of these studies. I have no opinion on short cranks versus standard cranks, but I have highlighted some sections that I found interesting. These studies focus on power output, which will no doubt be a bone of contention for Frank, but also efficiency and fatigue at different crank lengths and earlier studies tried to tailor bike design, including crank length, to the size of the cyclist/ So, for what it is worth, below are the abstracts of published scientific studies on short cranks (some of them not so short) that I could find on a PubMed search:

Thanks for your effort in this regards. I have made some comments earlier, this will complete the task. While I do not discount the importance of power it is my contention it is only a part of the equation for a cyclist optimizing performance and for the most part best performance will be had when both power and aerodynamics are considered and the two optimized together, as best as possible.

STUDY 1

Med Sci Sports Exerc. 2011 Sep;43(9):1689-97.
Effect of crank length on joint-specific power during maximal cycling.

Barratt PR, Korff T, Elmer SJ, Martin JC.
Centre for Sports Medicine and Human Performance, Brunel University, Uxbridge, United Kingdom.

…

PURPOSE:

The purpose of this study was to determine the effect of changes in crank length on joint-specific powers during short-term maximal cycling.

METHODS:

Fifteen trained cyclists performed maximal isokinetic cycling trials using crank lengths of 150, 165, 170, 175, and 190 mm. At each crank length, participants performed maximal trials at pedaling rates optimized for maximum power and at a constant pedaling rate of 120 rpm. Using pedal forces and limb kinematics, joint-specific powers were calculated via inverse dynamics and normalized to overall pedal power.

RESULTS:

ANOVAs revealed that crank length had no significant effect on relative joint-specific powers at the hip, knee, or ankle joints (P > 0.05) when pedaling rate was optimized. When pedaling rate was constant, crank length had a small but significant effect on hip and knee joint power (150 vs 190 mm only) (P < 0.05).

CONCLUSIONS:

These data demonstrate that crank length does not affect relative joint-specific power once the effects of pedaling rate and pedal speed are accounted for. Our results thereby substantiate previous findings that crank length per se is not an important determinant of maximum cycling power production.

If one doesn't care a whit about aerodynamics and want to ride what came with your bike this study is useful to your needs (unless, of course, one looks into how significant the effects were at 150 and 190 - was one or both higher?).

STUDY 2

Fatigue during maximal sprint cycling: unique role of cumulative contraction cycles.

Tomas A, Ross EZ, Martin JC.
Department of Exercise and Sport Science, the University of Utah, Salt Lake City, UT 84112-0920, USA.

Abstract

Maximal cycling power has been reported to decrease more rapidly when performed with increased pedaling rates. Increasing pedaling rate imposes two constraints on the neuromuscular system: 1) decreased time for muscle excitation and relaxation and 2) increased muscle shortening velocity. Using two crank lengths allows the effects of time and shortening velocity to be evaluated separately.

PURPOSES:

We conducted this investigation to determine whether the time available for excitation and relaxation or the muscle shortening velocity was mainly responsible for the increased rate of fatigue previously observed with increased pedaling rates and to evaluate the influence of other possible fatiguing constraints.

METHODS:

Seven trained cyclists performed 30-s maximal isokinetic cycling trials using two crank lengths: 120 and 220 mm. Pedaling rate was optimized for maximum power for each crank length: 135 rpm for the 120-mm cranks (1.7 m x s(-1) pedal speed) and 109 rpm for the 220-mm cranks (2.5 m x s(-1) pedal speed). Power was recorded with an SRM power meter.

RESULTS:

Crank length did not affect peak power: 999 +/- 276 W for the 120-mm crank versus 1001 +/- 289 W for the 220-mm crank. Fatigue index was greater (58.6% +/- 3.7% vs 52.4% +/- 4.8%, P < 0.01), and total work was less (20.0 +/- 1.8 vs 21.4 +/- 2.0 kJ, P < 0.01) with the higher pedaling rate-shorter crank condition. Regression analyses indicated that the power for the two conditions was most highly related to cumulative work (r2 = 0.94) and to cumulative cycles (r2 = 0.99).

CONCLUSIONS:

These results support previous findings and confirm that pedaling rate, rather than pedal speed, was the main factor influencing fatigue. Our novel result was that power decreased by a similar increment with each crank revolution for the two conditions, indicating that each maximal muscular contraction induced a similar amount of fatigue.

Even though there was no power difference discerned between 120 and 220 mm cranks this would be one of the limiting factors that causes power to begin to drop beyond a certain length, especially for endurance events.

STUDY 3

J Appl Physiol. 2002 Sep;93(3):823-8.
Determinants of metabolic cost during submaximal cycling.

McDaniel J, Durstine JL, Hand GA, Martin JC.
Department of Exercise Science, University of South Carolina, Columbia, South Carolina 29208, USA.

Abstract

The metabolic cost of producing submaximal cycling power has been reported to vary with pedaling rate. Pedaling rate, however, governs two physiological phenomena known to influence metabolic cost and efficiency: muscle shortening velocity and the frequency of muscle activation and relaxation. The purpose of this investigation was to determine the relative influence of those two phenomena on metabolic cost during submaximal cycling. Nine trained male cyclists performed submaximal cycling at power outputs intended to elicit 30, 60, and 90% of their individual lactate threshold at four pedaling rates (40, 60, 80, 100 rpm) with three different crank lengths (145, 170, and 195 mm). The combination of four pedaling rates and three crank lengths produced 12 pedal speeds ranging from 0.61 to 2.04 m/s. Metabolic cost was determined by indirect calorimetery, and power output and pedaling rate were recorded. A stepwise multiple linear regression procedure selected mechanical power output, pedal speed, and pedal speed squared as the main determinants of metabolic cost (R(2) = 0.99 +/- 0.01). Neither pedaling rate nor crank length significantly contributed to the regression model. The cost of unloaded cycling and delta efficiency were 150 metabolic watts and 24.7%, respectively, when data from all crank lengths and pedal speeds were included in a regression. Those values increased with increasing pedal speed and ranged from a low of 73 +/- 7 metabolic watts and 22.1 +/- 0.3% (145-mm cranks, 40 rpm) to a high of 297 +/- 23 metabolic watts and 26.6 +/- 0.7% (195-mm cranks, 100 rpm). These results suggest that mechanical power output and pedal speed, a marker for muscle shortening velocity, are the main determinants of metabolic cost during submaximal cycling, whereas pedaling rate (i.e., activation-relaxation rate) does not significantly contribute to metabolic cost.

The energy cost of unloaded cycling was smallest with the shortest cranks (200 watts less compared to the longest cranks/worst condition) Could we predict from this that there is then more energy available to produce power? And, what does this study do to the oft heard argument that pedaling doesn't have an energy cost? Blows it out of the water I would say.

STUDY 4

Eur J Appl Physiol. 2002 Jan;86(3):215-7.
Effects of crank length on maximal cycling power and optimal pedaling rate of boys aged 8-11 years.

Martin JC, Malina RM, Spirduso WW.
Department of Exercise and Sport Science, University of Utah, Salt Lake City 84112-0920, USA. Jim.Martin@health.utah.edu

Abstract

It is generally reported that cycle crank length affects maximal cycling power of adults and that optimal crank length is related to leg length. This suggests that the use of standard length cycle cranks may provide nonoptimal test conditions for children. The purpose of this study was to determine the effects of cycle-crank length on maximal cycling power and optimal pedaling rate of 17 boys aged 8-11 years. The boys performed maximal cycle ergometry with standard (170 mm) cycle cranks and with a crank length that was 20% of estimated leg length (LL20). Power produced when using the 170 mm cranks [mean (SEM)] [364 (18) W] did not differ from that produced with the LL20 cranks [366 (19)]. Optimal pedaling rate was significantly greater for the LL20 cranks [129 (4) rpm] than for the 170 mm cranks [114 (4) rpm]. These data suggest that standard 170 mm cranks do not compromise maximal power measurements in boys aged 8-11 years so that the test apparatus does not bias physiological or developmental inferences made from tests of maximal cycling power.

Another Martin study that only looks at Maximum power. Says nothing about sustainable power or what the effects of position are on the ability to generate power. It has little to do with my thoughts.

Thanks again for your efforts in finding these studies. I look forward to the comments of others on the specifics of these studies as they relate to this particular discussion

 

[FrankDay]

The study posted does just that if you agree with findings or not. you have done nothing to discredit it

???? Which study does just what?

 

[FrankDay]

Frank;

I don't discount your theory because there is simply no convincing evidence to support or reject it yet my friend. Meaning your presentation and logic is flawed. That is the point many of us are trying to convey to you. give me something to chew on

How can you proceed to pick apart a study with documented results based on a sample survey which supports both the pros and cons of it's assertions when in fact you do nothing of the sort in your own arguments? It's like coachfargo saying his students go faster because they are his students

elapid thanks for that study. nice post

I am still chewing on this one

Can we talk about this a little because it seems to support longer cranks right? am I reading this correctly? Study 2 btw

Study two is interesting. As I stated, this is the reason we just can't keep going shorter and shorter because we compensate for the loss of pedal speed (there is an optimum pedal speed) by increasing cadence. But, increasing cadence gives the muscles less recovery time between efforts. So, by this study, there is a limit as to how short one can go before the disadvantages start outweighing the advantages. The study does not address what that limit is however, especially for race durations and when in a racing position, especially time-trial position.

The other really interesting study to me in the batch, aside from 5 which I had earlier mentioned in starting this thread, is study 3, which demonstrates how much energy is wasted just making longer cranks go around. If this energy can be used instead to propel the bicycle this could easily explain why power doesn't drop off as everyone expects when crank length is shortened.

 

[Boeing]

Well one thing for sure; crank arm length is important


I still can't understand how you can credibly pick apart an argument without supporting your own Frank


Its simple math to me: Like recumbents; if they aint in Le Tour they can't be that efficient after all.

 

[FrankDay]

Well one thing for sure; crank arm length is important


I still can't understand how you can credibly pick apart an argument without supporting your own Frank


Its simple math to me: Like recumbents; if they aint in Le Tour they can't be that efficient after all.

Well, you have joined me now in "picking apart an argument" when you say "one thing for sure; crank arm length is important" even though you can't point to any specific study to support that statement.

The average researcher will tell you exactly what Martin said in his study, crank arm length is not very important for cyclists and they will cite the Martin study.

Let's say I was arguing that longer is better. Just as I can't produce any power when crank length gets down to zero it would not be possible to generate any power if crank length got longer than my leg length. So, there has to be a length (both long and short) where power starts to drop, where crank length gets either too long or too short for good power production. Now we have a range where power is more or less constant. If we want to fine tune that and see which crank is absolutely most powerful that is fine but the work involved is tedious and the advantage is small (even though it may not be a big advantage if you are going for KOM at the TDF such an advantage may be worth it). But, as long as we are within that range we will be very close to being able to achieve maximum power production and that will be fine for most if power is all they are interested in (which is probably the case for most of those who "train using power")

We then might want to look and see if crank length has any other effects on the cyclist. That is all I did and, lo, what did I find? Aerodynamics! Of course these thoughts were based upon standard aerodynamic principles (reducing frontal area and a better shape) but I also found anecdotal reports supporting my thoughts (John Cobb reported being able to drop the rider drag 30% converting an athlete to shorter cranks and moving him to a subsequent more compact position).

When we combine these two considerations then it becomes clear that the best combination is going to be the shortest crank one can go to before power begins to be lost because shorter crank lengths allows the rider to achieve better aerodynamic positions. The only question then becomes how short can the crank length go before any individual rider begins to lose substantial power? (edit: Of course, there is no big advantage to going shorter for any particular individual unless that individual intends to take advantage of this better aerodynamics potential.) This idea should not be particularly controversial yet here we are well beyond 1000 replies and I have had to put up with the standard onslaught of personal attacks for even making this claim.

Scientifically, not a single study looks at this combination change so there is zero "scientific evidence" against my contention. And, even though this also means there is no scientific evidence in support of my contention I believe I have plenty of "anecdotal evidence" to support what I am arguing. But, even if I didn't have that and all I had was a thought experiment I think I would still be on strong ground - after all that is how Einstein started wasn't it: thought experiments? And, those arguing against my contention focus on the power aspect alone, missing the point of argument entirely.

 

[lostintime]

+1. I know I shouldn't watch, but I am strangely drawn in just to read the ongoing saga. Like a soapie ... pervasive but nothing ever really changes.

yeah ...like a soapie !!

in this case .... "As The Crank Turns"